(4)Why use the extended-surface equipment in heat exchanger, and descript the kinds and its advantage. (4%)

(1)To write down the define of hydraulic radius and equivalent diameter , and what is the hydraulic radius for annulus between two concentric pipes? (4%)

(2)What are the wet-bulb temperature and dry-bulb temperature, and the relative volatility? (4%)

(3)Please interpret the dropwise and film type condensation? (4%)

(5)Define the reflux and the used reason in the operation, what are the minimum reflux ratio and optimum reflux ratio? (4%)

2. A cylinder (cross-sectional diameter of 0.01128 m) containing chloropicrin (CCl3NO2) is placed in a hood. The hood has a blower system that continually circulates dry air at a constant temperature 25℃ and 1 atm pressure. Originally, the liquid surface is 0.0388 m from the top of the cylinder. After one day the liquid level is 0.0412 m below the top. The vapor pressure and density of CCl3NO2 are 3178.3 N/m2 and 1650 kg/m3, estimate the substances diffusivity in air. Molecular weight of CCl3NO2 is 164.39. (20%)

(1)Calculate the moles of overhead product and bottom product per hour. (6%)

(2)The molal latent heats of steam is 939 cal/gmol and used for heating, how much steam is required per hour for the above cases, neglecting heat losses and assuming the reflux is a saturated liquid? (7%)

(3) If cooling water enters the condenser at 80°F and leaves at 150°F, how much cooling water is required?(7%)

4. A fan sends static air into a 45 m long； rectangular pipe of 200 mm x 300 mm. The air entering the pipe is 15℃and 750 mmHg absolute pressure, and the flow rate is 0.6 m3/s. What is the theoretical power required? For a smooth tube, f= 16/Re in laminar flow； f= in turbulent flow； Re is the Reynolds number. (20%)

5. What is flowing through a large circular conduit with a velocity profile given by the equation v = 9(1-r2/16) fps. What is the average water velocity in the 1.5-ft pipe? (10%)

110年 - 110 國立臺北科技大學_碩士班招生考試_化學工程與生物科技系化學工程碩士班(甲組)：單元操作與輸送現象#107422